High-precision micro-power digital pressure sensor (pressure code transducer) with RS-485 interface


Main characteristics

Primary converter

silicon strain gauge pressure sensor

Pressure measurement range
(at ambient temperature ‑40..+60 °C or ‑40..+170 °C)

overpressure (bar):
0.35; 1; 2; 3.5; 7; 20; 35; 70; 200; 350; 500
absolute (bar):
1; 2; 3.5; 7; 20; 35; 70; 200; 350; 500

Pressure measurement error in the whole range of medium temperatures

< ±0.1; ±0.05 %

Temperature error in the entire measurement range

< ±0.1 °C

Thermal inertia index

< 20 sec

Wiring diagram

4-wire connection with shielded signal cable (2-wire RS-485 line plus common ground wire connected to the shield and power wire)

Supply voltage

2.7..5.5 V

Maximum pulse current consumption in active mode

< 1.5 mA

Standby consumption current

< 4 uA

Average current consumption in the continious reading with a period of 30 sec

< 12 uA

Average current consumption in standby mode with continuous polling of other RS‑485 nodes

< 25 uA

Active mode consumption current (if you have an isolated RS-485)

< 2 mA

Standby consumption current (with isolated RS-485)

< 500 uA

Ambient temperature

-40..+70 °C

Start time after power up

< 100 msec

Measurement speed

up to 7 SPS

Material of protective reinforcement

stainless steel

Housing material

aluminium alloy

Immunity to dust and moisture

IP-65, IP-67

Link length

< 1500m (9600bps speed)

Data transfer rate (with an increase in speed of more than 9600bps (up to 3Mbps), the converter goes out of micro-power mode)

9600, 4800, 2400, 1200, 600bps

The number of devices on the RS-485 bus

up to 247

Highest degree of explosion protection


Type of protection

intrinsically safe electrical circuit

  • High-precision measuring device designed for remote automatic data collection using a standard communication protocol without special software.

  • Sensors comply with all safety requirements.

  • Power supply of the device is negligible and is carried out directly from the RS-485 bus. With a maximum network load (continuous serial polling of 247 devices), the total consumption in the RS-485 power supply circuit does not exceed 7 mA (for non-isolated RS-485 interface).

  • Isolated or non-isolated RS-485 interface. Communication protocol Modbus RTU (optionally it is possible to connect using other protocols based on the RS-485 interface). Up to 247 sensors in the network.

  • High noise immunity.

  • High reliability and long-term stability.

  • Designed for mass production.

Design features

Pressure sensor STV‑P‑485 consists of sensors block (sensitive elements for pressure and temperature) and electronic block, that are connected by a heat-resistant silicone cable with length from 0.3 to 2m. Sensors block located in a sealed cylindrical protective casing made of stainless steel with a diameter of 24.5mm. Electronic block placed in a sealed aluminum alloy case with dimensions of 56x41x32mm. Communication of the pressure sensor with the user is provided by the 8-pin block connector of POLSUN.

Interface and system integration features

The device combines a sensors block (sensing elements) and a transducer, which processes the readings from the sensors and transmits them via the RS-485 interface.

A platinum resistance thermocouple is used as the primary temperature sensor in the probe, whose data are used to compensate for the temperature error of the silicon strain-resistant pressure sensor.

The on-demand electronic unit converts the pressure and the temperature resistances data into digital code packets in the standard EIA/TIA RS-485. This makes it possible to build distributed control systems and process control systems without the use of additional converters using the standard network digital exchange protocol ModBUS RTU (

The electronic unit includes an ADC and a microcontroller, which has a programmed algorithm for converting pressure into a digital code with correction for temperature data. This algorithm includes a calibration procedure, correction of pressure sensor data based on calibration results, as well as additional service functions.

At the request of the network master (register reading procedure), the results of pressure and temperature measurements are given.

With one master device (PC or PLC) and one communication line, it is possible to take readings from many sensors in the network (up to 247), by sequential polling.

Areas of use

  • Machine building and metalworking

    • Power engineering

    • Production of technological equipment by industry

      • cold production (refrigeration and air conditioning)

      • heat production (heat engines and air conditioning)

      • heating networks

      • heat exchange equipment

    • Construction and municipal engineering

    • Agricultural engineering

    • Oil and gas engineering

      • equipment for oil refining

      • gas and oil transportation equipment

    • Chemical engineering

    • Timber industrial engineering

    • Automotive industry

    • Machine tool

    • Food industry equipment

    • Industry of household appliances and machines

    • Instrumentation

      • heat meters

      • gas meters and gas volume correctors

    • Radio and electronics industry

    • Electrical industry

  • Chemical and petrochemical industry

    • petrochemistry

    • agrochemistry

    • polymers and elastomers

    • pharmaceutical chemistry

    • perfumes and cosmetics

  • Fuel industry

    • gas industry

    • oil industry

  • Pulp and paper industry

  • Building materials industry

  • Food industry

  • Medical industry